Usethis calculatorto compare water heater energy costs between tank water heaters and tankless water heaters, based on planned usage.
Smarter Hot Water is Sustainable, Responsible Water heating can account for 14 percent of energy usage in the home, making it the biggest energy guzzler after the heating and air conditioning system. The water heating solution for major bathroom remodeling directly impacts the sustainability and long-term operating costs for your clients.
As with other green remodeling guidelines, the choice of water heating solution is best determined by the available resources and climate, weighing up-front and installation costs vs. long-term operating costs.
Sustainability and Tankless Water Heaters
Tankless water heaters outperform tank water heaters when it comes to sustainability. Tankless is also the better hot water engine to deliver the in-home spa experience, providing a continuous supply of hot water at a consistent, preset temperature as long as the demand exists. (You do know that water - hot or otherwise - isn't really "endless," right?)
While replacing a tank water heater with a tankless water heater in a remodel can be complex, the savings in operating costs are significant - from 25% to 40% less than required to operate a conventional tank-type water heater, since there is no standby heat losses:
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Tankless water heaters match the use of energy to your client's use of hot water. They will never heat any water while away on business or vacation, or even just out for the day.
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This is a main reason that tankless water heaters burn natural gas or liquid propane far more efficiently than tank heaters, boasting an Energy Factor above .80.
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The energy efficiency of tankless water heaters does not come with a trade-off in performance. Your clients will never run out of hot water.
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Tankless water heaters are smaller than tank heaters, and can be located closer to the point of use. Water is not wasted down the drain, as you wait for hot water.
Sustainability and Tank Water Heaters
Clients who have tank water heaters older than 10 years may be thrilled with their reliability and longevity, but those older tank water heaters are considerably less efficient than today's advanced technology. Encourage clients with older tank units to upgrade to new high-efficiency water heaters, which have a minimum Energy Factor (EF) of 0.63.
Clean-burning, low-emissions tank water heaters are now available. Such water heaters have slashed nitrous oxide (NOx) emissions by 75 percent, compared with older low NOx models, fully complying with Southern California requirements, the most stringent in the nation.
Look for technologies that reduce corrosion and harmful sediment in tank water heaters, a byproduct of the fact that they store and heat water continuously, year after year.
Sustainability and Solar Water Heaters Is solar water heating reliable enough to recommend to your clients? Depending on your locale, solar water heating may very well be able to create satisfying client experiences and conserve more resources than tank water heaters or tankless water heaters. Technology has reached the point where solar water heating systems were named a Top 10 building technology for 2007 by the Partnership for Advancing Technology in Housing (PATH).
Solar water heating systems can be "passive," where the water flows from the collection site to the storage tank via gravity or some other non-mechanical means; or "active," which uses a circulating pump to move water through the system. Active may also be called "forced circulation," and it obviously requires more energy than passive systems.
Passive systems are limited to warmer climates, however, where there is no risk of freezing. Active, forced-circulation types are the most common in the United States, because they can function throughout the country, even in colder Northern areas. In warmer climes, a passive solar water heating system will be more efficient to operate and less complex to install.
Note that even the most efficient solar water heaters sometimes require auxiliary heating (boosting). This may be because of a large, late-in-the-day hot water usage or a long period of extensive cloud cover. Whether electric, gas or some other fuel type, a booster can be quite effective at enabling a solar water heater to provide a year-round supply of steaming hot water, but this backup does adds more energy requirements and costs.
